Upgrade readme action from v1 to v2

Author: goruha

.github/workflows/shared-readme.yml

@@ -60,7 +60,7 @@ jobs:
           fetch-depth: 0
           token: ${{ steps.github-app.outputs.token }}
 
-      - uses: cloudposse-github-actions/readme@v1
+      - uses: cloudposse-github-actions/readme@v2
         with:
           token: ${{ steps.github-app.outputs.token }}
           readme_enabled: true